If Vera is hungry enough for this he can win it. Randy Couture has the ability to take the heart away from fighters who aren't ready for a war. If Vera isn't prepared mentally, or has an false-inflated confidence, he will lose.
I'm not sure Vera can stop Randy from taking him down habitually, I don't care about his BJJ, I don't think it will be enough against Randy from the bottom. Vera needs to strike from a distance, refuse Randy's takedowns, and knock him out if gets the opportunity. Vera should be improving his power, because he WILL be able to hit Randy in this fight, whether it will matter is something different.